Doubly projecting neurons of the dorsal column nuclei.

In a sample of 1700 neurons recorded from the dorsal column nuclei of the cat, 44 (2.6%) were found to send an axon down the dorsal spinal cord. Fully 70% of these caudally projecting neurons also sent an axon to the ventral thalamus. Nearly all had small cutaneous receptive fields distally on the forelimb and displayed response properties similar to other neurons of the dorsal column nuclei. Most were isolated along the lateral and medial margins of the cuneate nucleus rostral to the obex, and many were excited or inhibited by pericruciate cerebral stimulation. A few clearly were excited monosynaptically from the contralateral cerebral cortex at a latency that required the largest pyramidal tract fibers. These neurons probably comprise an important subset that regulates the flow of sensory information in spinal and brainstem somatic sensory pathways.